Hello everyone, all day today I’ve been chasing the symptoms trying to find the cause of my problem. Was hoping you folks could visualize my observations and offer your thoughts if you don’t mind.
I have a York condenser, cooling only,
that I believe has a restriction inside of the outdoor unit. At startup, within 15 seconds my liquid line pressure drops down to 100, then 75, then 65 and offends the low pressure switch causing a temporary shutdown. Conversely at the same time my suction line pressure goes higher than I think it should. System behaved as if it was grossly undercharged no matter what I checked or did. Yes my indoor blower fan was functional.
York YCG24B21SB, 17 Seer, 2 ton cooling only.
3/4” and 3/8” copper lineset about 16 feet long.
First Co air handler 30k btu with hydro coil 30HBXB-HW. Installed vertically. Txv that’s OEM with the First Co air handler, Sporlan CP7325.
Factory charge for this ODU is 3 pounds 10 ounces (for a lineset up to 15 feet I believe) of r410a. Design pressures 448 high side, 236 low side.
Compressor was running 5.0 amps
Emerson ZP20K6E-PVF-130
Deducting refrigerant wasn’t going to help me.
I added 2 ounces of refrigerant (3 pounds 12 ounces total charge now) because the indoor coil is a 1/2 ton large and because the lineset was a foot or two long. Saw no difference.
I then added 6 ounces more, then another 6 ounces. Total charge now at that point was 4 pounds 12 ounces. Upon restarting the compressor I still had the same problem of the liquid line pressure dropping fast and too much. All things considered it was expected for the liquid line pressure to be really high now and that’s exactly what I found. Within that 15 seconds of runtime when my liquid line pressure was sinking my suction line pressure was skyrocketing above 400 psi when it was only 79°F outside.
I believe that my liquid line inside of the outdoor unit is restricted or somewhere further down that path but before the compressor inlet. Maybe up to and including the liquid-line service-valve. Somewhere like the 3/8” inlet to the aluminum manifold into the condenser coil, the manifold itself, all or most of the micro channel coil, the outlet manifold of the coil, it’s 1/2” o.d. Copper line leaving the coil going into the compressor or a stuck intake valve in the compressor.
My txv isn’t stuck closed. I suspected the tiny little filter dryer inside of the condenser unit may have been restricted, and I also noticed it was installed backwards to flow direction. It seems clear to me that refrigerant is stacking up at the service port of the liquid line service valve and new liquid refrigerant is not entering the liquid line.
So I recover the entire charge. Take a picture of the backwards-installed filter dryer before I partially disassemble the condenser housing in order to remove the suction service valve and the filter dryer. Using air pressure from my lips I was able to demonstrate that the filter drier flows much more freely in the direction that the flow arrow points. When I blew air backwards into the filter dryer as it was installed, I found a slight restriction which I guessed was 20 to 25% restriction.
Not anywhere near as big of a problem-cause as I thought it was going to be. But I’m going to make it right regardless. So I follow the path of refrigerant flow to eliminate possibilities.
I installed a new and larger filter dryer on the liquid line outside of condenser unit. I made absolutely certain that there was no restriction into, through and out of my liquid line service valve before attaching the outlet of that inside of the outdoor unit. I even puckered up and tried to blow air into the outdoor coil, but it was completely resistant to that.
Makes me wonder if there’s a shipping cap concealed at the inlet of the coil manifold that they forgot to take out before attaching the copper suction line. That transition between the copper suction line downstream of that service valve, and before the aluminum manifold header is concealed with a black piece of heat shrink tubing about 1 inch long. I then attached my new 3/8 copper bypass from the outlet of the suction-line service-valve and the 3/8” copper inlet stub just before the outdoor coil. RLS refrigerant press fittings driven by a Rigid RP200 short throw press tool.
Because the system was completely evacuated and my service valves are wide open I did an initial 250 psi pressure test and ate lunch.
Then I fully discharged that pressure twice out through the 1/4” flare at my suction-line service-valve while checking my Txv valve in two ways even though I expected the problem is not a stuck metering device, based on the symptoms explained way above.
First TXV test with the sensing bulb removed and immersed into a can of ice water. I expected the valve to be closed and found that to be reasonably true because I dumped pretty much all of my nitrogen pressure out through the suction-line service-valve in about 20 seconds while the liquid line pressure trailed down much more slowly. That’s because the TXV was “closed” mostly.
Second Txv test I pulled the sensing bulb out of the ice water can and warmed it up in my hand for about a minute. Left it dangling in the airstream that was probably about 75°F. Recharged both high and low side, including the outdoor unit with 250 psi of nitrogen. I expected with a warm sensing bulb to have a TXV it’s pretty much wide-open and that’s what I found. When I opened my manifold gauge to vent the liquid-line service-valve to atmosphere. I found that the pressure on the suction side drop much more quickly than last time, and it was very much nearly in unison with the high side pressure. Exactly as you’d expect with a wide open metering device. I still haven’t found the cause of the blockage outside of my unproven suspicion up to this point. Expecting the problem to continue but I’ve got to give it a try.
Pulled a triple evaluation procedure which included an oil change to the vacuum pump between my second and third pull downs during the nitrogen break. Below 200 µm and it held for 5 minutes while not rising above 300 µm. Nice and tight.
At this point it’s clear that the backwards installed filter dryer was not the cause of my problem. At the conclusion of my triple evaluation process I weigh in a refrigerant charge of 3 lbs. 12 oz. and still find the exact same problems happening.
The suction line pressure goes way up to like 350 within 15 seconds.
The liquid line drops to 100 and then 65 psi within 15 seconds. Overcharging it does nothing to increase the running pressure of the liquid line. Liquid line isn’t getting any refrigerant as I see it.
It did the same thing at some point today when I removed the refrigerant and ran just nitrogen and oil at 220 psi for starters for 15 seconds.
There’s something causing pressure to measurably stack up at the suction valve service port.
No doubt there’s nothing leaving out the liquid line. It’s behaving as if the liquid line service valve is closed. The valve was back seated (all the way up) so I tried a restart with the valve mid seated and that made no difference.
Because it’s an aluminum micro channel coil and a copper pipe, there’s some sort of black heat shrink over the adapter between those two metals.
I called my indoor sales guy at the supply shack who is very technically inclined and he understood everything I was telling him, but he was leaning towards the possibility of the TXV inside being the actual cause of the problem. Anything but the ODU he sold me!
If the TXV was stuck closed, for example, refrigerant would stack up before that metering device and I feel that would actually drop pressure measured at the suction service valve, not raise it. A stuck-closed txv would also raise pressure on the liquid line I believe and those two things are opposite of what’s actually happening.
During a warm sensing bulb moment the txv isn’t locking closed “tight as a bulls ass”. It’s bleeding through a little bit. I presume that is normal and certainly not a cause of my problem.
I plan to return to the job site Friday and kick ass problems ass. I am considering bringing with me a makeshift air handler unit as a bypass test device that I’m going pipe up with a 6 foot lineset at the ODU. I’m going to take an old coil and screw down through the drain pan to retain it to a blower fan assembly that still has the galvanized panel that it hangs off of. I need to look through that section of the scrap pile to find one that’s reasonably compatible in size. If it happens to be a fixed piston, orifice style at the chatleff valve, which size piston should I use? This is just a temporary test to show that there’s likely nothing wrong with the existing lineset, indoor coil or metering device.
Is my thought a possibility that a test cap/shipping cap may have been left on the outdoor coil inlet? This could have been just before the line worker at the assembly plant attached copper piping to the aluminum coil manifolds,
What might I be doing wrong?
What else should I check?
I have a York condenser, cooling only,
that I believe has a restriction inside of the outdoor unit. At startup, within 15 seconds my liquid line pressure drops down to 100, then 75, then 65 and offends the low pressure switch causing a temporary shutdown. Conversely at the same time my suction line pressure goes higher than I think it should. System behaved as if it was grossly undercharged no matter what I checked or did. Yes my indoor blower fan was functional.
York YCG24B21SB, 17 Seer, 2 ton cooling only.
3/4” and 3/8” copper lineset about 16 feet long.
First Co air handler 30k btu with hydro coil 30HBXB-HW. Installed vertically. Txv that’s OEM with the First Co air handler, Sporlan CP7325.
Factory charge for this ODU is 3 pounds 10 ounces (for a lineset up to 15 feet I believe) of r410a. Design pressures 448 high side, 236 low side.
Compressor was running 5.0 amps
Emerson ZP20K6E-PVF-130
Deducting refrigerant wasn’t going to help me.
I added 2 ounces of refrigerant (3 pounds 12 ounces total charge now) because the indoor coil is a 1/2 ton large and because the lineset was a foot or two long. Saw no difference.
I then added 6 ounces more, then another 6 ounces. Total charge now at that point was 4 pounds 12 ounces. Upon restarting the compressor I still had the same problem of the liquid line pressure dropping fast and too much. All things considered it was expected for the liquid line pressure to be really high now and that’s exactly what I found. Within that 15 seconds of runtime when my liquid line pressure was sinking my suction line pressure was skyrocketing above 400 psi when it was only 79°F outside.
I believe that my liquid line inside of the outdoor unit is restricted or somewhere further down that path but before the compressor inlet. Maybe up to and including the liquid-line service-valve. Somewhere like the 3/8” inlet to the aluminum manifold into the condenser coil, the manifold itself, all or most of the micro channel coil, the outlet manifold of the coil, it’s 1/2” o.d. Copper line leaving the coil going into the compressor or a stuck intake valve in the compressor.
My txv isn’t stuck closed. I suspected the tiny little filter dryer inside of the condenser unit may have been restricted, and I also noticed it was installed backwards to flow direction. It seems clear to me that refrigerant is stacking up at the service port of the liquid line service valve and new liquid refrigerant is not entering the liquid line.
So I recover the entire charge. Take a picture of the backwards-installed filter dryer before I partially disassemble the condenser housing in order to remove the suction service valve and the filter dryer. Using air pressure from my lips I was able to demonstrate that the filter drier flows much more freely in the direction that the flow arrow points. When I blew air backwards into the filter dryer as it was installed, I found a slight restriction which I guessed was 20 to 25% restriction.
Not anywhere near as big of a problem-cause as I thought it was going to be. But I’m going to make it right regardless. So I follow the path of refrigerant flow to eliminate possibilities.
I installed a new and larger filter dryer on the liquid line outside of condenser unit. I made absolutely certain that there was no restriction into, through and out of my liquid line service valve before attaching the outlet of that inside of the outdoor unit. I even puckered up and tried to blow air into the outdoor coil, but it was completely resistant to that.
Makes me wonder if there’s a shipping cap concealed at the inlet of the coil manifold that they forgot to take out before attaching the copper suction line. That transition between the copper suction line downstream of that service valve, and before the aluminum manifold header is concealed with a black piece of heat shrink tubing about 1 inch long. I then attached my new 3/8 copper bypass from the outlet of the suction-line service-valve and the 3/8” copper inlet stub just before the outdoor coil. RLS refrigerant press fittings driven by a Rigid RP200 short throw press tool.
Because the system was completely evacuated and my service valves are wide open I did an initial 250 psi pressure test and ate lunch.
Then I fully discharged that pressure twice out through the 1/4” flare at my suction-line service-valve while checking my Txv valve in two ways even though I expected the problem is not a stuck metering device, based on the symptoms explained way above.
First TXV test with the sensing bulb removed and immersed into a can of ice water. I expected the valve to be closed and found that to be reasonably true because I dumped pretty much all of my nitrogen pressure out through the suction-line service-valve in about 20 seconds while the liquid line pressure trailed down much more slowly. That’s because the TXV was “closed” mostly.
Second Txv test I pulled the sensing bulb out of the ice water can and warmed it up in my hand for about a minute. Left it dangling in the airstream that was probably about 75°F. Recharged both high and low side, including the outdoor unit with 250 psi of nitrogen. I expected with a warm sensing bulb to have a TXV it’s pretty much wide-open and that’s what I found. When I opened my manifold gauge to vent the liquid-line service-valve to atmosphere. I found that the pressure on the suction side drop much more quickly than last time, and it was very much nearly in unison with the high side pressure. Exactly as you’d expect with a wide open metering device. I still haven’t found the cause of the blockage outside of my unproven suspicion up to this point. Expecting the problem to continue but I’ve got to give it a try.
Pulled a triple evaluation procedure which included an oil change to the vacuum pump between my second and third pull downs during the nitrogen break. Below 200 µm and it held for 5 minutes while not rising above 300 µm. Nice and tight.
At this point it’s clear that the backwards installed filter dryer was not the cause of my problem. At the conclusion of my triple evaluation process I weigh in a refrigerant charge of 3 lbs. 12 oz. and still find the exact same problems happening.
The suction line pressure goes way up to like 350 within 15 seconds.
The liquid line drops to 100 and then 65 psi within 15 seconds. Overcharging it does nothing to increase the running pressure of the liquid line. Liquid line isn’t getting any refrigerant as I see it.
It did the same thing at some point today when I removed the refrigerant and ran just nitrogen and oil at 220 psi for starters for 15 seconds.
There’s something causing pressure to measurably stack up at the suction valve service port.
No doubt there’s nothing leaving out the liquid line. It’s behaving as if the liquid line service valve is closed. The valve was back seated (all the way up) so I tried a restart with the valve mid seated and that made no difference.
Because it’s an aluminum micro channel coil and a copper pipe, there’s some sort of black heat shrink over the adapter between those two metals.
I called my indoor sales guy at the supply shack who is very technically inclined and he understood everything I was telling him, but he was leaning towards the possibility of the TXV inside being the actual cause of the problem. Anything but the ODU he sold me!
If the TXV was stuck closed, for example, refrigerant would stack up before that metering device and I feel that would actually drop pressure measured at the suction service valve, not raise it. A stuck-closed txv would also raise pressure on the liquid line I believe and those two things are opposite of what’s actually happening.
During a warm sensing bulb moment the txv isn’t locking closed “tight as a bulls ass”. It’s bleeding through a little bit. I presume that is normal and certainly not a cause of my problem.
I plan to return to the job site Friday and kick ass problems ass. I am considering bringing with me a makeshift air handler unit as a bypass test device that I’m going pipe up with a 6 foot lineset at the ODU. I’m going to take an old coil and screw down through the drain pan to retain it to a blower fan assembly that still has the galvanized panel that it hangs off of. I need to look through that section of the scrap pile to find one that’s reasonably compatible in size. If it happens to be a fixed piston, orifice style at the chatleff valve, which size piston should I use? This is just a temporary test to show that there’s likely nothing wrong with the existing lineset, indoor coil or metering device.
Is my thought a possibility that a test cap/shipping cap may have been left on the outdoor coil inlet? This could have been just before the line worker at the assembly plant attached copper piping to the aluminum coil manifolds,
What might I be doing wrong?
What else should I check?
